Various steel, aluminum and other metal molds or dies are produced for the plastic, injection molding and die casting industries. These molds or dies often contain difficult to reach areas like thin slots or ribs that need to have a finish like the other larger, more reachable surfaces. To do this, the mold maker or polisher will often take a larger abrasive stone (e.g., a 1/16.times.1/4.times.6 in) and form a thin point on the end of it. This tool works well to remove the scratches and EDM deposits in the rib but the ground tip is extremely fragile and will snap off easily. Thus the polisher has to stop and reform a new tip. Mold makers use numerous other tools to accomplish this difficult polishing task. Some of these are thin diamond files, thin brass tools with lapping compound, emery paper and various homemade tools. All of these have major disadvantages.
A product designed for hard to reach finishing, e.g., slot and rib finishing or polishing is being sold under the name Supra Ceramic Stone. It is a thin (1 mm.times.4 mm.times.100 mm and other sizes: 1 mm.times.6 mm.times.100 mm; 1 mm .times.10 mm.times.100 mm, and the like), fiber product. It is described as a composite material consisting of long ceramic fibers and a thermo-setting resin. It contains none of the "abrasive grit" or porosity that is found in a traditional abrasive stone. The way this specialized ceramic fiber is fabricated gives it abrasiveness to polish these difficult ribs and slots. Ordinary epoxy bonded glass fibers (fiber reinforced plastics, FRP) albeit strong, do not cut. The "Supra" stone's advantage over an ordinary mold stone is its strength and rigidity for such a thin part while having the ability to abrade metals. A 1 mm.times.4 mm.times.100 mm abrasive mold and die polishing stone would snap like chalk under similar conditions. Disadvantages of the Supra Stone are (1) it does not cut quite as well as a resin or vitrified bonded abrasive stick and (2) the raw materials price is very high.
U.S. Pat. No. 5,233,794, assigned to Nippon Steel Corporation, describes a rotary tool for cutting, drilling, grinding or polishing metallic or non-metallic materials. It is made of a compact material which consists of inorganic fiber reinforced plastic containing 50-81 vol. % of inorganic long fibers. The remaining portion of the compact material consists of a thermo-setting resin matrix. The Supra Stone material described above may be described in this patent.
U.S. Pat. No. 3,867,795, assigned to Norton Company, describes a reinforced resin bonded abrasive depressed and straight center wheels for portable snagging grinders. It is described as having a primary abrading portion extending along the bottom side to the peripheral grinding face occupying a portion of a pre-determined thickness of the wheel and having resin bonded primary abrasive particles of alumina-zirconia therein. It also has a secondary abrading portion bonded to and extending from the primary abrading portion to the top side and peripheral grinding face of the wheel and has resin bonded secondary abrasive particles of a secondary abrasive material which differs from and of less durability than alumina-zirconia abrasive material.
U.S. Pat. No. 4,218,851, assigned to Norton Company, describes a high speed rotatable abrasive body which is a resin bonded abrasive body. Described is an abrasive body which has an elongated rectangular shape similar to a center part or a circular grinding wheel from which two identical diametrically opposed arcuate segments have been removed. The abrasive body has a central portion with diametrically opposite arcuate spindle flange mounting segments with tapered surfaces projecting from opposite edges of diametrically opposite grinding portions extending substantially at right angles therefrom to diametrically opposite peripheral grinding surfaces. Situated within and axially spaced between opposite parallel sides 24 of the abrasive body are a number of layers of reinforcing material 26.
Other patents of interest are U.S. Pat. Nos. 5,249,566; 3,716,950; 2,804,733; 3,684,215; and 4,259,089.
None of the references or the prior art describes a mold and die polishing and finishing tool having multiple layers of abrading surface held in position with longitudinally placed unidirectional graphite fibers which are present in an adhesive resin bonding matrix which secures the layers together.
It is an object of the present invention to have a mold and die polishing and finishing tool having top and bottom abrasive layers with an adhesive resin bonding matrix containing graphite fiber layer between which secures the layers together.